In vivo cell tracking imaging of direct labeled stem cells using hexadecyl-4-[^123,124I]iodobenzoate in rat myocardium

Objectives Monitoring of transplanted stem cells for cardiac repair is important part in regenerative medicine. This study is aimed to track the transplanted adipose derived stem cells (ADSCs) in rat myocardium using hexadecyl-4-[^123,124I]iodobenzoate ([^123,124I]HIB) mediated direct labeling method in vivo.

Methods [^{123, 124}I]HIB was used to direct-radiolabel ADSCs by absorption into cell membrane. In vitro stability of [¹²³I]HIB labeled ADSCs was investigated by activity check in supernatant, and cell viability was determined by trypan blue exclusion test. Radio-labeled ADSCs were intramuscularly injected in left ventricle. In vivo imaging was each followed for 30 and 60 min by using small animal PET/SPECT/CT. After 5 ([¹²³I]HIB labeled ADSCs) and 18 days ([¹²⁴I]HIB labeled ADSCs) post-transplantation, animals were sacrificed and heart tissues were fixed for histological analysis.

Results Cell-labeling efficiency to [^123,124I]HIB was over 50%. In vitro stability and cell viability of [¹²³I]HIB labeled ADSCs was over 90% for 24 h. In PET/SPECT/CT imaging, tracking of ADSCs labeled with [¹²³I]HIB was possible for 2 days, and tracking of ADSCs labeled with [¹²⁴I]HIB was possible for 9 days. Through histological analysis, the transplanted [¹²³I]HIB labeled ADSCs were detected in rat myocardium.

Conclusions [^{123, 124}I]HIB was efficiently labeled to ADSCs and [¹²³I]HIB labeled ADSCs was successfully engrafted in cardiac muscle and possible tracking for 2 days, and [¹²⁴I]HIB labeled ADSCs was possible tracking for 9 days. These results suggested that [^{123, 124}I]HIB can be used as direct labeling agent for early cell tracking of transplanted stem cells